Recently, due to advancements in surgical techniques and surgical equipment, surgeries for performing various treatments (also called microsurgery) while observing an affected site with an observation device for medical use, such as an endoscope or a surgical microscope, are coming to be conducted frequently. Also, such observation devices for medical use are not limited to devices that enable optical observation of the affected area, and also include devices that display an image of the affected area captured by an imaging section (camera) or the like as an electronic image on a display such as a monitor.
Also, some imaging sections like the above are provided with an auto focus (AF) function that automatically brings a subject into focus. For example, Patent Literature 1 discloses an example of an endoscopic device provided with an auto focus function.